1. Field of Invention
This invention relates to devices used for the treatment of waste water. More specifically, this invention relates to a removable, two-part filtering system used for the filtering of liquid effluent contained in a septic tank.
2. Prior Art
Waste water discharged from commercial or residential property containing both liquid and solid wastes is typically collected in a waste water collector, such as a septic tank. In such septic tanks, the liquid and solids are generally distributed into three layers: an upper horizontal scum layer, a lower horizontal sludge layer, and a relatively clear, horizontal, liquid effluent layer between the two other layers. During operation of the septic tank systems, liquids from this horizontal, liquid effluent layer are intermittently discharged from the septic tank. During such discharge the solids contained within the septic tank are preferably retained in the septic tank to be decomposed during the normal operation of the system. As needed, the septic tanks may be cleaned to remove any settled solids.
During normal operations, some solids become mixed into the relatively clear horizontal, liquid effluent layer. Solids migrate into this layer associated with gas bubbles produced during metabolism of material contained in the lower sludge layer. In addition, large solids with specific gravities similar to that of the liquid effluent layer may also be discharged. These solids may be discharged with the effluent, if not filtered out of the effluent. Excess solids discharged with the effluent may gradually degrade the effectiveness of the entire septic system.
To reduce the likelihood of discharge of solids from the septic system, a number of different filtering devices for liquid effluent have been developed. For example, cylindrical mesh screen filtering systems which surround a gravity flow outlet system and discharge pump are disclosed in U.S. Pat. Nos. 5,207,896 and 4,439,323.
Other filtering devices, which may be placed within a septic system, which use a filtering system different from a mesh screen are disclosed, for example, in U.S. Pat. Nos. 5,683,577, 5,482,621 and 5,382,357. These patents disclose filtration of effluent using a specific flow pattern for the effluent through an open bottom of the filter element, out the sides of the filter element into an annular space adjacent to the filter element, and finally to the discharge opening of the device for discharging the filtered effluent from the septic system. See also U.S. Pat. No. 5,690,824.
Other systems for filtering solids from the effluent of a septic system utilizing a stacked disk dam system as the filtering system are disclosed in U.S. Pat. Nos. 5,593,584, 5,582,716, 5,207,896, 4,710,295, 3,332,552 and 2,900,084. See also U.S. Pat. Nos. 5,413,706, 5,409,604, 5,306,425, 5,264,120 and 5,207,896 which disclose both a mesh screen and a disk dam system to filter the effluent.
U.S. Pat. No. 5,795,472 discloses a multistage filter device which includes removable side walls which have a filtering capacity. U.S. Pat. Nos. 5,759,393 and 5,591,331 disclose a filtering system comprising a plurality of vertically extending removable side walls, each of which contains a filtering screen for filtering the effluent. In addition, U.S. Pat. No. 5,736,035 discloses an outlet filter including a two-piece filter element.
A filter system containing a removable filter with diagonal slits for filtering effluent in a septic system is disclosed in U.S. Pat. No. 5,569,387.
In addition to systems which utilize a single filter element within a filter system, multiple filter element systems for filtering effluent in a septic system are disclosed in U.S. Pat. Nos. 5,762,793, 5,635,064, 5,580,453 and 5,492,635. Each of these patents describes a specific flow pattern for the effluent entering the filter system and exiting through a discharge opening in the housing of the filter system.
Because of limitations on the flow of the effluent through these prior art systems, problems often arise from clogging of the filters which necessitates frequent cleaning of the systems. Some of the screen filter systems can even collapse during normal use, also necessitating cleaning and/or replacement. It has been generally recognized that filter systems clog for several reasons. The system may clog from entrainment of solid particles in the effluent stream. Alternatively, the openings in the filter system may be clogged from the growth of a biological film on its surface. Elimination of the biological film significantly enhances the life expectancy of the filter system. The incorporation of a biocide into a plastic piping to kill or limit the growth of bacteria and other microorganisms present in a water irrigation system was disclosed in U.S. Pat. No. 5,332,160. See U.S. Pat. No. 5,192,037 for the use of copper sulfate for a similar system. See also U.S. Pat. No. 3,288,674 for the use of 10,10xe2x80x2 oxydiphenoxarsine as a bactericide for use in plastics and U.S. Pat. No. 3,069,252 for the use of this material to control growth.
Other problems may arise when the filters of these filter systems are removed from the septic tank for cleaning. When the filtering capability of these systems is removed, these systems fail to provide any backup mechanism to filter effluent being discharged during the cleaning process. This may result in an undesired discharge of solids through the discharge opening into the lateral system.
Thus, a need exists for a more efficient filtration system for filtering solids from the effluent of a septic system, especially during cleaning of the filter for the system, which overcomes the problems present in the prior systems.
Accordingly, it is an object of this invention to disclose a filter system for filtering the effluent present in a waste water system.
It is a further object of this invention to disclose a filtering system for filtering effluent from a waste water system which filtering system contains a significant amount of filtering surface, thus reducing the likelihood of clogging of the filters during normal operation.
It is a further object of this invention to disclose a filtering system containing primary and secondary filter elements which are easy to clean and replace.
It is a still further object of this invention to disclose a filtering system utilizing a primary and secondary filters, one secured within the other filter, such that the effluent passing through these filters is filtered continually, even when one of the filters has been removed for cleaning.
It is a further object of this invention to disclose a filtering system which permits a significant volume of liquid effluent to be filtered by the filtering system with a reduced likelihood of clogging of the filtering system.
It is a still further object of the invention to disclose a treatment for the filtering system that reduces the growth of a biological film on the filtering system during normal operations.
It is a further object of the invention to disclose a primary and secondary filtering system treated with a chemical biocide which reduces the growth of a biological film on the filtering system.
These and other objects and features of the present invention will become apparent to those skilled in the art from a consideration of the following detailed description, drawings and claims. The description, along with the accompanying drawings, provides a selected example of construction of the device to illustrate the invention.
In accordance with the present invention there is provided a removable filtering system for filtering liquid effluent contained in a waste water system, which includes a tubular, outer secondary filter, which is secured within an effluent discharge pipe fitting, wherein the outer secondary filter includes a central opening passing vertically therethrough; an inner primary filter, which is slidingly engaged within the central opening in the outer secondary filter; and a filtering connection element, secured to the outer secondary filter against an inner surface of the discharge pipe fitting, wherein the filtering connection element filters effluent passing upward through the discharge pipe fitting and wherein upon removal of the inner primary filter from the discharge pipe, the outer secondary filter continues to filter effluent passing through the discharge pipe fitting. Thus, even when the inner primary filter has been removed from the system for cleaning and/or replacement, effluent cannot be discharged out of the septic tank without first being filtered by the outer secondary filter.
In an alternative embodiment, the filtering connection element is an integral element of a specialized outlet pipe fitting.
In a further alternative embodiment, a second removable, filtering system can be secured to the first filtering system to provide additional filtration for effluent present in the septic tank. In this embodiment, a second effluent discharge pipe fitting is secured to the first effluent discharge pipe fitting and the second effluent discharge pipe fitting has contained therein a second outer secondary filter, a second inner primary filter and a second filtering connection element.
In a further alternative embodiment, one or more of the filters contains a biocide which retards the growth of a biological film on these filters.